For years, Jimmy Webb has been coy when asked to explain that cake left out in the rain and the rest of the lyrics to his classic "MacArthur Park." It's been recorded by some of the industry's most celebrated names: Frank Sinatra, Tony Bennett, Diana Ross, The Four Tops and, most recently, Carrie Underwood.

Many tales have evolved, in the media and online to explain the genesis of the song. Here are but a few:

* They're a metaphor for the end of his relationship with a relative of Linda Ronstadt's who later got married in that Los Angeles park on a rainy day.

* Webb was annoyed by British record executives, so he extended the song past seven minutes, something unheard of on AM radio.

* He bet Richard Harris a Rolls-Royce that he could write a No. 1 song for him.

* And not long ago, Simon Cowell supposedly said Webb had told a friend of his the song is about sex and drugs.

So which ideas are apocryphal, and are any true? We asked not only Webb but also his wife of a decade, Laura Savini.

"Well, it's all true," Webb says, laughing. "There are little bits and pieces of the true story there, but what I've resorted to, because it's really turned into a kind of lifetime of talking about 'MacArthur Park,' whether I want to or not. My fallback position after all these years is I will tell you that I've told deliberately false stories to people.

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"I've also tried to tell the truth, which is that it's just a song about a girlfriend of mine, Susie Horton, and this place on Wilshire Boulevard where we used to have lunch, which is called MacArthur Park. And the truth is that everything in the song was visible. There's nothing in it that's fabricated. The old men playing checkers by the trees, the cake that was left out in the rain, all of the things that are talked about in the song are things I actually saw. And so it's a kind of musical collage of this whole love affair that kind of went down in MacArthur Park.

"And I remember that that was also when I wrote 'By the Time I Get to Phoenix' because this affair was winding down to a kind of dreary close, and I was thinking, 'Well, I'll just go back to Oklahoma,' and so I wrote 'By the Time I Get to Phoenix.' Of course, I never even got in the car and turned on the engine to go back to Oklahoma. But it's related to 'MacArthur Park' in that sense. It comes from the same period when I was experiencing things and pretty much transferring them immediately into music.

"My writing technique, my style, is a lot different now, so in a way, it's a lot more accessible and easier to understand. Back then, I was kind of like an emotional machine, like whatever was going on inside me would bubble out of the piano and onto paper.

"It was issued as rather a challenge to me from Bones Howe, who was the producer of The Association, that could I do an extended, classically oriented piece that could be played on the radio, and if I could, then 'something that has different movements.' So it was more his urging me than it was some spontaneous 'Oh, gee, I think I'll write a rock classical masterpiece.'"

Savini, a Public Television host-producer, is almost as good a storyteller as her renowned songwriting husband. Nearly five decades after the song's release, she says she's constantly getting queries about it.

"When people see he's my husband," she says, "that's always the first question I get: 'What's "MacArthur Park" mean?' And I always say it's an abstract painting, an impressionist painting. It's art, but in a musical form. You make it what you want it to be. Jimmy plays it down, but it's a heartbreaking song when you listen to just him sing it and you hear all the words without all the orchestrations. It blows your mind -- oh, my God, all the pain in that song."

To underscore the song's place in history -- it finished No. 8 on WABC radio's chart of 1968 hits -- Savini notes that last year Webb's picture appeared on the front page of the Los Angeles Times when he performed the song in the actual MacArthur Park.

Savini also proudly points out that an entire "Late Show With David Letterman" in July was devoted to the song. Paul Shaffer's bassist, Will Lee, sang along with the show's band and Webb at the harpsichord-piano keyboards -- plus a 23-piece orchestra:

"This whole thing came about because David Letterman is a fan of Jimmy's and loves the song. Instead of doing a Top 10 list, he did a whole segment of the show talking about 'MacArthur Park' and how he heard three versions on Sirius radio when he was with his son: the Richard Harris one, the Donna Summer version -- which he said he had never heard before -- and the Jimmy/Brian Wilson one, and he just went bonkers for the song.

"They rehearsed and planned this segment for months, and the producer said it's maybe only the second time in history that David brought in a whole symphony orchestra. He made a huge deal of it. They called the whole night 'MacArthur Park Night.' They even had a big cake -- with sweet, green icing -- that Will Lee climbed at the end, playing the guitar and singing.

"The whole thing was a tiny bit tongue-in-cheek, but it was a huge tribute to the song and how much David liked it, and he wanted his son to understand the song. It was an unbelievable thing -- everyone was so excited about it. We got a handwritten note from David a couple of days later thanking us and saying what an incredible experience it was for him."

On Webb's latest CD, "Still Within the Sound of My Voice," Webb is joined not only by the Beach Boys' Wilson but by others singing Webb favorites. Carly Simon, for example, performs his "Easy for You to Say."

"It's very funny," Savini recalls. "The song is gorgeous -- it'll give you the chills. And when I heard the track, I just looked at him and said, 'Did you have an affair with her?' Because you just hear this emotion of this heartbreak in the song -- it's really fantastic." So how did Webb respond? "He said, 'Noooo.' But they've been good friends a long time."

Finally, Savini also offered a sneak peek into the memoir that Webb is writing. "I describe it as a cross between 'The Grapes of Wrath' and 'Fear and Loathing in Las Vegas,'" she says. "It's a story of growing up in Oklahoma with nothing and then becoming this crazy, fast-car-driving, drug-taking star who's 19 and has everything you can imagine."